generally you can establish the "power" of a weapon by its caliber this works great with small arms, once you get in to bigger guns ie artillery and ships guns there is more to it then just caliber. but even with small arms the power can range widly with each bullet comes different powder loads, different lead weights, and different types of bullets.
A BB gun would be more powerful
The 17 pound gun was more powerful than the 90mm gun.
Other than a toy gun or water gun, the next most powerful one a citizen can have without a permit is a "B.B. gun".
Yes.
It depends on a couple of factors, but generally speaking, a gun.
the measurements of a round are not measured in that way, nor does the size of the gun have anything to do with how powerful it is
577 T Rex
star cannon
Yes the ray gun is lethal, the ray gun is one of the most powerful guns in nazi zombies
Machine Guns, like any other gun (with the possible exception of an air soft gun) could seriously harm, and even kill you if at point blank range. Any gun could kill you, so, yes. a machine gun is powerful.
If you are referring to the present, today's most powerful sub-machine gun is the H&K UMP .45 cal sub-machine gun, or the Kriss Vector SMG. if you are referring to the past however then its undeniably the Tommy Gun. also a .45 cal sub-machine gun.
10 gauge shotgun